Radio receiver



March 14, 1939. J. DREYFUS RADIO RECEIVER Original Filed Dec. 6, 1934 IN VENT OR. DregFuQ ATTORNEY.

BY a i 4 Patented Mar. 14, 1939 UNITED STATES PATENT OFFICE RADIO RECEIVER Jean Dreyfus, Paris, France 3 Claims.

This application is a division of application Serial No. 756,378 filed December 6, 1934.

The present invention relates to improvements in radio receivers and objects of the invention are a better utilization of the space available to reduce the size and. improving the compactness. of the receiver without impairing the quality of its acoustic reproduction.

A more specific object of the invention is the provision of an improved sound pervious tuning dial adapted for mounting over a sound transmitting opening of the receiver such as the orifice of a loud speaker as generally described in my U. S. Patent 2,044,759.

Another object is the provision of a sound pervious tuning dial mounted over a sound transmitting opening of the receiver, said tuning dial having further features of construction adapted to improve or modify the quality of the sounds generated by the loud speaker.

Still another object is the provision of means associated with a loud speaker embodied in a radio receiver or the like for controlling or modifying the acoustic characteristics of the sounds reproduced by the receiver.

Further objects and features of the invention will become apparent from the following description taken with reference to the accompanying drawing illustrating a radio receiver with the improvements of the invention embodied therein.

In the drawing, wherein like reference numerals identify like parts in both views Figure 1 represents a vertical cross-section through a receiver showing only those parts essential for the understanding of the invention.

Figure 2 is a front view of the receiver shown in Figure 1.

The receiver illustrated comprises a housing or cabinet II) which may be of wood or the like, a chassis ll serving as a support and metallic shield for the circuit elements excepting the amplifying tubes, and a loud speaker l3 mounted over an opening in the front wall of the cabinet in accordance with well known practice in receiver design. The loud speaker shown is of the dynamic type and comprises a casing having a cup shaped rear portion l4 containing a magnet core with an exciting winding I6 and a voice coil H, the latter being attached to the cone shaped diaphragm If! so as to be able to move freely over the magnet core It in a manner well known. The outer edge of the diaphragm is secured to the casing of the speaker, the latter being in turn connected to the cabinet by any suitable means such as by means of metal screws or the like.

Clamped between the outer flange of the loud speaker and the adjacent mounting support or baffle or secured in any other desired manner is a perforated disc or plate 19 which may be of metal, Celluloid, fibre, ebcnite or any other suitable material. The perforations of disc ii) in the example shown comprise outer arcuate ope-nings 20 the edges of which approximately correspond to the outer contour of the loud speaker and a central circular opening 2|. The latter is designed so as to be adapted to pass the higher sound notes while the lower notes have a tendency to pass through the outer larger openings 20 just described. In order to further increase the efficiency of the sounds passed by the plate I9 and enable its use additionally as a tuning dial for the receiver, I have shown further slot-like perforations 22 and 23 of the disc l9 extending radially from the center towards the periphery. The slots 23 may serve as calibrating marks for the tuning indicia for indicating the stations to which the receiver is tuned. Thus in the drawing a tuning scale from. 200-600 meters has been shown covering the broadcast wave band. For the latter purpose, I have shown a movable pointer 24 rotatably mounted behind the plate IS in case the latter is of transparent or translucent material such as of Celluloid or the like. If the plate I9 is of opaque material, the pointer is preferably arranged in front of the plate by extending its shaft 25 through the opening 2|.

The perforations or openings 2|, 22 and 23 act in providing an acoustic impedance presented to the sound waves radiated by the diaphragm l8 and may be designed and distributed such as in the manner shown so as to pass the sound spectrum generated by the loud speaker or to modify the response characteristic to have a desired shape by preferredly passing sound components of predetermined frequency. Alternatively, the perforations or openings may be regarded as pressure transformers or secondary emission sources designed and arranged to obtain a desired over-all response characteristic.

In the example illustrated the shaft 25 is mounted in a central perforation of the loud speaker core which serves as a bearing for the shaft whose rear end is driven in synchronism with a variable tuning element of the receiver such as tuning condenser 26 mounted within the chassis H through any suitable driving mechanism. The latter in the example shown comprises a pair of cam pulleys 21 and 28, the

former secured to the rear end of the shaft of condenser 26 and the latter being secured to the rear end of the shaft for the pointer 24. The pulleys are connected through a wire or cord 29 having its opposite ends secured each to one of the pulleys so as to wind and unwind therefrom as the condenser is adjusted by operating the adjusting knob 30 secured to the front end of the condenser shaft.

In order to effect return of the shaft 25 in the contrary direction I have provided a spring 3i having one end attached to the chassis II and having its other end attached to a pulley fixedly connected to the pulley 28 to be wound upon and unwound therefrom as described in greater detail in the parent application.

In order to prevent the plate or dial I9 and the tuning indicia thereon from being visible during non-use of the receiver and with the View to improve the esthetic appearance of the receiver, I have furthermore shown a cover 32 of cloth, fabric or equivalent material having evenly distributed pores or perforations to be pervious to sounds placed in front of the disc or plate l9, thus normally concealing the disc and the tuning indicia thereon, but allowing the latter to shine through if a lamp 33 mounted on a bracket 34 behind the disc 19 is lit during the operating condition of the receiver. The cover 32 may be secured to the casing in any desirable manner and is preferably held by clamping against the disc l9 by means of a frame 35 secured in the opening of the cabinet.

It will be apparent from the above that the invention is not limited to the specific details of construction, arrangements of parts shown and materials used, but that many modifications and variations may be resorted to difiering from the specific showing presented herein for illustration and coming within the broader scope and spirit of the invention as expressed in the appended claims.

I claim:

1. In a radio receiver, a loud speaker, a plate having tuning indicia thereon and occupying a sound emitting orifice of the receiver, said plate having openings forming acoustic paths designed tobe eifective in passing the sounds generated by said loud speaker, and a movable indicator arranged to cooperate with said indicia to indicate the station to which the receiver is tuned.

2. In a radio receiver, a loud speaker, at translucent plate having tuning indicia thereon and occupying a sound emitting orifice of the receiver, said plate having openings forming acoustic paths designed to be effective in passing the sounds generated by said loud speaker, a sound pervious fabric covering said plate to normally conceal said tuning indicia, and a light disposed behind said plate capable of rendering the tuning indicia upon said plate visible by the translucent character of said plate and fabric.

3. In a radio receiver, a loud speaker, a plate having tuning indicia thereon and occupying a sound emitting orifice of the receiver, said plate having openings including slots designed to be effective in passing sounds generated by said loud speaker, said slots serving as calibration marks for said tuning indicia, and a movable indicator arranged to cooperate with said tuning indicia to indicate the station to which the receiver is tuned.

JEAN DREYFUS. 

